Three-dimensional memory device having pocket structure in memory string and method for forming the same

Abstract

Embodiments of 3D memory devices having a pocket structure in memory strings and methods for forming the same are disclosed. In an example, a 3D memory device includes a substrate, a selective epitaxial layer on the substrate, a memory stack including interleaved conductive layers and dielectric layers on the selective epitaxial layer, and a memory string including a channel structure extending vertically in the memory stack and a pocket structure extending vertically in the selective epitaxial layer. The memory string includes a semiconductor channel extending vertically in the channel structure, and extending vertically and laterally in the pocket structure and in contact with the selective epitaxial layer.